NASA selects new biotechnology projects for development

NASA selects new biotechnology experiments for development

Current, former NASA/Marshall scientists
chosen

Mar. 8, 1999:
Squeezing through a tight spot and going against the flow
are among the biotechnology techniques that will be explored
by seven current and former researchers at NASA's Marshall Space
Flight Center.

They are among 48 scientists selected under the latest NASA
Research Announcement (NRA) focusing on biotechnology. Principal
areas of research are protein crystal growth and cell science.

One project touches on both of those fields. Dr. Robert Snyder
is going to refine a system for purifying proteins and cells.
Snyder is a former chief of the microgravity science division
at NASA/Marshall's Space Sciences Laboratory. He now works with
New Century Pharmaceuticals Inc. in Huntsville.

Right: Charles Walker, then with
McDonnell Douglas Astronautics, operates a continuous flow electrophoresis
system aboard the Space Shuttle in the early 1980s. Although
electrophoresis in space showed great promise, it was overtaken
by genetic engineering. A retired NASA/Marshall scientist believes
that lessons from this and other flight can be applied in a more
advanced space-based electrophoresis system.

He's studying electrophoresis, a technique
that passes an electrical field through a fluid as it flows from
one end of a chamber to another. The electric field makes molecules
and cells move across the fluid. The speed depends on the molecule
or cell's size, mass, or surface charge. Like a prism separating
white light into its colors, an electrophoretic system can separate
cells and proteins. But it's limited on Earth by convection caused
by heating from the electric field.

NASA and McDonnell Douglas experimented with electrophoresis
aboard the Space Shuttle in the 1980s, but encountered unexpected
problems that kept the technique form reaching its full potential.

"We've always felt very strongly that electrophoresis
should be designed to take maximum advantage of microgravity
in space," he explained. "Previously, we just adapted
1-g equipment designed for use on Earth."

Snyder and Percy Rhodes, another NASA retiree also working
at New Century Pharmaceuticals, are designing a new electrophoretic
system that adds a flowfield and uses the electric field to focus
the materials he wants to separate.

"There's an
incredible interest on the part of the protein crystal growth
community for purer proteins" so they can eliminate impurities
that cause defects, Snyder explained. "Also, a variety of
cells are extremely interesting for fractionating. You want to
get purified cells, for certain treatments, so you don't overload
the patient with other components that they don't need."

Left: The fragility of a protein
molecule is illustrated by a ribbon diagram that depicts the
molecule's components as a series of strips the join, twist,
and intertwine. This complexity makes the geometry of a protein
- or a drug that interacts with a protein - very specific. It's
like picking a lock at the atomic scale.

Once you have the purified proteins, much remains to be learned
about how they assemble into crystals, and how that process might
be improved.

"We're going to study how important different sites on
proteins are to the crystallization process," said Dr. Marc
Pusey of NASA/Marshall's Space Sciences Laboratory. Molecules
form crystals because of atomic attractions between specific
points on the molecule. Proteins - also called macromolecules
because of their size - may have a large number (up to 70 points
or more for even a small protein) that must connect in a highly
specific manner. But no one is sure which ones are most critical
for crystal growth.

"By going in at the genetic level, we can study where
the molecules are joined the strongest or the weakest,"
Dr. Pusey explained. "We may be able to alter some of these
points - without affecting the function of the proteins - to
make better contacts and improve the quality of the crystals.
We can also study how important these contacts are to the nucleation
and crystal growth process, and learn about the factors which
drive crystal growth itself."

Dr. Robert Naumann, also a former chief of the microgravity
science division, is working on growing better crystals by putting
them in a tight spot. Naumann now works at the University of
Alabama in Huntsville.

"One of the reasons we don't always get good crystals
in space is that we can't always limit the movement of nutrient
to the crystal," he explained. In this case, nutrient means
proteins in solution. As the molecules join the expand ing crystal,
the concentration in that small region is depleted, and more
molecules diffuse from the richer areas.

"It's like people going into a soccer stadium,"
Naumann explained. "If you have a few doors, the people
have plenty of time to get in and find their seats. If you open
it wide, they rush in and sit anywhere." And that can result
in crystals that grow with less than ideal arrangements.

Naumann's experiment will develop a growth technique that
will limit the access that the molecules have and thus give the
molecules more time to find their seats. It will take longer
to grow crystals, but the result should be improved quality for
crystals grown both on Earth and in space.

Dr. Russell Judge of NASA/Marshall also is looking at how
microgravity improves crystal quality.

"We want to determine how the growth of crystals effect
their quality," Judge said, "and then take that into
space to see how microgravity is enhancing the growth characteristics
that lead to good crystals. From this we want to develop techniques,
so that by observing crystal growth on the ground, we can predict
which proteins are likely to benefit the most from microgravity
crystallization."

He will experiment with a number of materials representing
different classes of proteins including, commercial enzymes and
food storage proteins.

Human recombinant insulin crystals
grown in space (left) are larger and better ordered than those
grown on Earth (right). This helps scientists as they try to
decipher the molecular structure of the insulin molecule by beaming
X-rays through the crystals onto film or a special camera. The
dots relate to the arrangement of atoms within the molecules.
Crystals with internal defects, which often happens on Earth,
yield blurry patterns that allow uncertainty about the arrangement.
This makes it difficult to design drugs that have a specific
purpose and fewer side effects. Research on insulin, for example,
is leading to therapies that are gentler on diabetics that older
methods. These crystals were grown under the sponsorship of NASA's
Space Product Development program.

Left:
Within samples the size of rain drops grow protein crystals that
may lead to improved therapies for a range of illnesses.

Dr. Craig E. Kundrot, a senior scientist in the Laboratory
for Structural Biology, will optimize microgravity growth procedures
to improve the quality of problematic crystals that have resisted
efforts to grow better specimens in space.

"So far, we have used microgravity experiments to make
good crystals better," Kundrot said. "But we have not
tried to make poor ones better." He will work on three types
of ribonucleic acid, two proteins, and a protein-DNA complex.

"They all have different problems," Kundrot said.
"In one system, only one experiment in ten gives a crystal
good enough for x-ray diffraction studies. Another has a diffusion
scatter that swamps and fogs those nice spots in the diffraction
image."

Others are so fragile that they break when being mounted for
study, and another has a tendency to "twin," spontaneously
become Siamese twins instead of a single crystal.

"Also, I believe that going from poorly diffracting crystals
grown on the ground to good ones grown in space is the most attractive
use of space from the pharmaceutical industries' point of view,"
Kundrot said.

Another aspect of the work is searching for new crystallization
conditions in space.

"There are good reasons to believe that it is easier
to find conditions for growing crystals in space rather than
on the ground," he continued. "The space 'haystack'
is smaller than the earth 'haystack' in this version of the 'needle
in the haystack' problem. If true, this would also be of commercial
interest.

Dr. Daniel C. Carter of New Century Pharmaceuticals Inc.,
Huntsville, former director of the Laboratory for Structural
Biology, also was selected. He will investigate "Protein
Crystal Growth Facility-Based Microgravity Hardware: Science
and Applications."